Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life

Aftab A Khan; Abdulaziz A Al-Kheraif; Abdullah M Al-Shehri; Eija Säilynoja; Pekka K Vallittu

doi:10.1016/j.jmbbm.2017.11.038

Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life

J Mech Behav Biomed Mater. 2018 Feb:78:414-419. doi: 10.1016/j.jmbbm.2017.11.038. Epub 2017 Nov 26.

Authors

Aftab A Khan¹, Abdulaziz A Al-Kheraif², Abdullah M Al-Shehri³, Eija Säilynoja⁴, Pekka K Vallittu⁵

Affiliations

¹ Dental Biomaterials Research Chair, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia. Electronic address: aakjk@hotmail.com.
² Dental Biomaterials Research Chair, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
³ Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
⁴ Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland; Stick Tech Ltd - Member of GC Group, Turku, Finland.
⁵ Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland; Welfare Division, Turku, Finland.

PMID: 29223038
DOI: 10.1016/j.jmbbm.2017.11.038

Abstract

This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as "stage 1-5". To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (P<0.001). The regression coefficient suggests nanohardness increased on average by 0.039GPa for every storage group. The increased nanohardness values in the core region of 6-months and 2-years stored prepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC.

Keywords: Fiber-reinforced composite; Monomer; Nanohardness; Polymethyl (methacrylate); Resin composite; Semi-interpenetrating polymer network.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Analysis of Variance
Elastic Modulus
Hardness
Materials Testing
Mechanical Phenomena*
Polymethyl Methacrylate / chemistry*
Surface Properties
Temperature
Time Factors

Substances

Polymethyl Methacrylate